Combination hole center finder and center punch



June 5, 1956 COMBINATION HOLE CENTER FINDER AND CENTER PUNCH Filed May 17, 1955 2' 27 \I I, 7 l7 15 E\j@ i "E I 20 2 35' 24 2? "'"H I5 l'iw A 1 W '9' 5 '72 A 25 1 17a. 2 g; m 18% Ii? mun a I. "/9 z fidwardLLocheiri 17 BY} Z ATTORNEY.

E. L. LOCKHART 2,748,492

United States Patent GOMBINATION HOLE CENTER FINDER AND. CENTER PUNCH Edward L. Lockhart, Covington, Va.

- Application May17, 1955, Serial No. 509,004

6 Claims. (Cl. 33-191) This invention relates to tools for locating the center of a hole and punching an indentation in the center of the base of the hole.

The main object of the invention is the provision of a novel, improved and useful simple tool to locate the center of a hole in the base of a piece of heavy machinery being installed, so that the center of the hole may be punched and tapped for drilling in the base plate on which the machine is set and in the location in which it is to be permanently positioned. Without using such a tool it is a difficult and protracted operation to locate the center of the hole to be drilled in the base plate, and the common way of determining the center is subject to considerable error.

Another object of the invention is the provision of the improved tool mentioned above, with a minimum number of parts and in such form that it is readily and inexpensively manufactured as a precision tool.

Still another object of the invention is the provision of such a tool in the form of a plurality of legs, preferably four, which are hinged at their upper ends to a collar which is slidable on a threaded axial stem, with the further provision of a substantially identical collar threaded on the stern below the first collar, whereby movement of the stem upward within the first collar spreads the legs outward, and with the provision of further means whereby the stem may be struck with a hammer to punch a center mark in the hole and on the plate on which the legs rest, the legs having first been spread until their lower ends engage the circumferential wall of the hole.

The above as well as additional objects will be clarified in the following description wherein reference numerals refer to like-numbered parts in the accompanying drawing. It is to be noted that the drawing is intended solely for the purpose of illustration and that it is therefore neither desired nor intended to limit the invention necessarily to any or all of the exact details of construction shown except insofar as they may be deemed essential to the invention.

Referring briefly to the drawing, Fig. 1 is a perspective view of a tool embodying the features of the present invention and illustrating its application.

Fig. 2 is a longitudinal sectional view through the axis of the tool.

Fig. 3 is a sectional view taken on the line 33 of Fig. 2.

Referring in detail to the drawing, the numeral indicates a base plate on which a heavy machine is to be bolted. Merely for the sake of illustration and by way of example, it is to be assumed that at 11 is shown a portion or extension of the base or frame of the machine, the same being built with suitable holes for bolting the machine to the base plate, one such hole being shown at 12.

The tool of the present invention comprises a plurality of circumferentially equidistant legs 13 having transverse openings 14 through their upper ends. A collar 15 has 2,748,492 Patented June 5,, 19.56.

2. a like number, of circumferentially equidistant radial projections 16 each of which is provided, intermediate its Width, with a; radial slot, 11 in which the upper end: of a leg 13 registers. The two. arms 18 of which each projection 16 isthus formed. owing to. the bifurcation of the projection by the- Slot L7, are. provided with aligned passages 19 which are alsoaligned with, the leg opening 14; Through, eachof the aligned openings 19, 14, 19of each projection 16 and it s ,leg-1'3 a pin 20 is passed; thuspivoting' each; leg on a; projection 16ofthe collar-15.

A threaded stern. 21, havingv a, tapering lower end 22 terminating in, a, pointed end. 23, passes, slidably through h smoo p ing of. h c llar 15..

A ec member: 25.- iszid n ical t he collar 15: in all respects except that it lacks the passages 19 and that it is internally threaded on the stem 21. To simplify the description, pertinent parts of the member or nut 25 which are identical to parts of the collar 15, are indicated by the same reference numeral followed by the subscript a. The legs 13 thus normally register slidably in the slots 17a of the nut 25.

A knurled nut 26 is threaded on the stem 21 above the collar 15, and a coiled spring loosely surrounds the stem between the nut 26 and the collar 15. The upper extremity 28 of the stem is also knurled.

It is now apparent that, assuming by way of example that the various movable parts of the tool are in their positions shown in Fig. 2, if the collar 15 is held in one hand and the handle 28 of the stem is grasped in the other hand and raised with respect to the collar, the rising nut 25 will cause the legs 13 to be spread. If, on the other hand, the handle 28 is lowered with respect to the collar 15, the legs 13 will be free to move toward each other. To facilitate the latter movement of the legs, a rubber band 29 may be mounted around the legs and thus tend to bring them together.

In applying the tool to the purpose of the invention, as illustrated in Fig. l, the stem 21 is first lowered with respect to the collar 15 a distance sufiicient to bring the lower ends of the legs 13 into a common circle which is of smaller diameter than the hole 12. Then the stem is raised with respect to the collar 15 until the lower extremities of the legs 13 engage the circumferential wall of the hole 12, as shown in Fig. 1. In case the tip 23 of the stem, in the latter position of the legs, is too far from the base plate 10 within the hole 12, then rotation of the stem will gradually lower the stem toward the base plate, as it passed freely through the collar 15. The nut 26 is tightened down against the spring 27 a sufiicient distance to partly compress the spring. Finally, the upper end of the stem is struck a smart blow with a hammer to cause the tip 23 to punch a hole in the base plate, which hole will lie in the exact center of the hole 12, so that the hole, not shown, may be readily drilled into the base plate in alignment with the hole 12.

The above is given merely as an example of how the tool may be used in attaining the objects of the invention, but it is not necessary to follow the same steps or the exact sequence of steps to position the tool as shown in Fig. 1, ready for punching the center mark in the base plate.

I claim:

1. A tool of the class and for the purpose described, comprising an elongated normally vertical threaded stem having a handle portion on the upper end thereof and having the lower extremity thereof tapered substantially to a point, a collar slidably mounted on said stem, a plurality of circumferentially equidistant radial projections on said collar, a like plurality of elongated legs having their upper ends pivotally connected to said projections on axes tangential to a common imaginary circle coaxial with the stem, a nut threaded on said stem below said collar and having the same plurality of radial projections circumferentially equidistant from each other, each of said last-named projections being vertically bifurcated to provide slots therein, each of said legs registering slidably inone of said slots, and a nut threaded on said stern above said collar.

2. The tool set forth in claim 1, said collar projections being vertically bifurcated to provide slots therein, said upper ends of said legs being positioned in said lastnamed slots, each of said collar projections having a pin passing therethrough and through the upper end of the leg in the slot thereof thereby pivotally connecting the legs to the collar as aforesaid.

3. The tool set forth in claim 1, said collar projections being vertically bifurcated to provide slots therein, said upper ends of said legs being positioned in said lastnarned slots, each of saidcollar projections having a pin passing therethrough and through the upper end of the leg in the slot thereof thereby pivotally connecting the legs to the collar as aforesaid, said stem having a coiled spring surrounding the same between said collar and said last-named nut.

4. The tool set forth in claim 1, having an elastic band surrounding and in contact with said legs thereby normally urging said legs inward toward parallelism with said stem.

5. The tool set forth in claim 1, said stem having a coiled compression spring surrounding the same between said collar and said last-named nut.

6. The tool set forth in claim 1, said stem having a coiled compression spring surrounding the same between said collar and said last-named nut, and an elastic band surrounding and in contact with said legs thereby normally urging said legs toward parallelism with said stem.

No references cited. 

